Physical Therapy

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Physical Therapy and Rehabilitation

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Background and purpose: The purpose of this study was to determine the relationship between patient disability levels following anterior cruciate ligament reconstruction (ACLR) and closed kinetic chain performance as measured through a single leg hop for distance test, a 45-second sagittal plane hop test, and a 45-second frontal plane hop test.

Methods: Sixteen subjects, all cadets at the U.S. Air Force Academy who had undergone unilateral ACLR, participated in this study (10 males, 6 females, age=21.7±1.2 years, height=178.3±8.7 cm, weight=79.8±14.3 kg). The Knee Outcome Survey Sports Activity Scale (SAS) was used as our disability measure. The tests used to measure closed kinetic chain performance were the single leg hop test for distance and a 45-second sagittal and frontal plane hop test, which required subjects to hop back and forth over a strip of athletic tape in the required direction (front to back and side to side) as many times as possible during a 45-second period.

Results: The mean time from ACLR to testing for subjects in this study was 41.44±14.96 months (range =24 to 77 months). While no significant relationship existed between the SAS scores and the percent lower extremity differences for the single leg hop test or the 45-second frontal plane hop test, a significant relationship was noted between the SAS scores and the percent lower extremity differences for the 45-seccond sagittal plane hop test (r=0.51, P<0.05).

Conclusion: These findings indicate that the 45-second sagittal plane hop test could potentially be a useful clinical test in assessing a patient’s disability level after ACLR, particularly if used in conjunction with other clinical assessment techniques.


anterior cruciate ligament reconstruction, outcome, closed kinetic chain




© 2020 Ross et al; licensee Herbert Publications Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.



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